ML20027B503

Forwards LER 82-067/03L-0.Detailed Event Analysis Encl

ML20027B503
Person / Time
Site:	McGuire
Issue date:	09/10/1982
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20027B504	List: ML20027B503 ML20027B505
References
NUDOCS 8209210141
Download: ML20027B503 (3)

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CitAMI,oTTI:. N.C. 28242 II AI. II. TUCKEH TER_EPHONE vua.mensorst 32 sea 17 P l: $ 3 (70-1) 373-4 Nil September 10, 1982 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Re: McGuire Nuclear Station Unit 1 Docket No. 50-369

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/82-67. This report concerns T.S.3.3.2, "The Engineered Safety Feature Actuation System (ESFAS) instrumentation channels and interlocks shown in Table 3.3-3 shall be operable with their trip setpoints set consistent with the values shown in the trip setpoint column of Table 3.3-4...". This incident was considered to be of no significance with respect to the health and safety of the public.

Very truly yours,

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flal B. Tucker PBN/jfw Attachment cc: Director Records Center Office of Management and Program Analysis Institute of Nuclear Power Operations U. S. Nuclear Regulatory Commission 1820 Water Place Washington, D. C. 20555 Atlanta, Georgia 30339 Mr. P. R. Bemis Senior Resident Inspector McGuire Nuclear Station 8209210;y/y #ed fp

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DUKE POWER COMPANY McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NO. 82-67 REPORT DATE: September 10, 1982 FACILITY: McGuire Unit 1, Cornelius, NC IDENTIFICATION: Failure of Train A Auxiliary Feedwater Pump Turbine (AFPT)

Low Suction Pressure Switches DESCRIPTION: On August 13, 1982, with Unit 1 at 50% power, two AFPT low suction pressure switches were declared inoperable pursuant to Technical Specification 3.3.2. The switches failed to perform properly during performance of the " Auxiliary Feedwater Low Suction Functional Test". This incident is attributed to Component Failure / Malfunction. The pressure switches were recalibrated and the functional test was successfully completed.

On August 26, 1982, while reviewing past work requests on the pressure switches as part of the incident investigation, a discrepancy between setpoints was noted.

The presence of a water leg not included in the August 13, 1982 calibration was verified. Technicians recalibrated the pressure switches 'r include the water leg and verified operability. Due to the incorrect calibration of August 13, 1982, the pressure switches were inoperable for an additional 13 days. This event was a result of Personnel Error.

EVALUATION; The purpose of the pressure switches is to provide 'A' train Nuclear Service Water to the Auxiliary Feedwater Pump Turbine on low suction pressure (loss i of water supply). When the technicians isolated and vented the switches during the performance of the functional test on August 13, 1982, the decrease to zero psig pressure failed to open a valve (via switch actuation) as required. The technicians manually operated the pressure switches and the valve opened, indicating that one or both pressure switches had failed to actuate during the test. No mechanical problems were observed on either switch, but the switches were out of calibration.

Although this may have resulted from instrument drift, the setpoints appeared to have been misadjusted. A technician obtained the setpoints from the Mechanical Instrument List and the pressure switches were calibrated to 2 psig decreasing.

A replacement was obtained for one of the switches and it was bench calibrated to expedite return to service (the removed pressu- switch was later tested, set to 2 psig decreasing, and verified functional).

On August 26, 1982, a review of previous calibrations revealed a setpoint of 5 psig, decreasing, for the switches. This setpoint included 2 psig for the process plus 3 psig to compensate for an 80 inch water column between the suction piping center-line (instrument tap) and the lower elevation of the pressure switches. This water leg could account for both of the pressure switches being found apparently misad-justed on August 13, 1982. The effective setpoint (relative to the process) of the August 13 calibration was 2 psig minus the 3 psig water leg, or -1 psig. This violated the allowable value of > 1 psig (Technical Specification Table 3.3-4, item 7.f.) and would have inhibited swap over to 'A' train Nuclear Service Water. The pressure switches were recalibrated to 5 psig decreasing.

Report No. 82-67 Page 2 It is probable that the failure of August 13, 1982 was limited to only one pressure switch since both switches must actuate to open the valve. The pressure switches are United Electric Type J302 (Model 552 -refers to range). Type J302 pressure switches have a good service history.

The inadvertant omission of water leg compensation was a personnel error directly attributable to a lack of training in the use of setpoints obtained from the Mechanical Instrument List. Unbalanced water legs must be identified, measured, and, if necessary, added to the process setpoint (or range) obtained from the list.

Although training at the Technical Training Center includes the effect of water legs on instrumentation, newer technicians are not fully aware that water legs are normally not included in the Mechanical Instrument List.

Many procedures are generic and do not include setpoints (this is the case with the

" Calibration Procedure for Electric Pressure Switch Type J302), thereby requiring proper use of the Mechanical Instrument List.

SAFETY ANALYSIS: The purpose of the Auxiliary Feedwater System is to provide a backup to the Main Feedwater system to insure adequate dissipation of energy from the Reactor Coolant System when the main heat sinks (turbine generator or steam dump and main feedwater) are unavailable. At no time during the event did a loss of the assured supply (nuclear service water) to the Auxiliary Feedwater Pump Turbine occur. Although the pressure switch failures prevented 'A' train Nuclear Service Water from being available in the event of an emergency, 'B' train Nuclear Service Water was available.

Additionally, both 'A' and 'B' trains of Nuclear Service Water were available to the Motor Driven Auxiliary Feedwater Pumps. Therefore, the health and safety of the public were unaffected by this incident.

CORRECTIVE ACTION: The action taken to correct the switch malfunction was to calibrate the two pressure switches. Proper operation of the switches was verified August 26, 1982 by successfully completing the calibration at the appropriate set-point. Since United Electric Type J302 pressure switches have given reliable service and it is probable that only one pressure switch actually malfunctioned, this action is sufficient.

To prevent future instances of incorrect calibration management will notify all technicians, ir, crew meetings, of the necessity to identify and, if necessary, add water legs to satpoints and ranges obtained from the Mechanical Instrument List.

This information vill also be incorporated into the Orientation training program conducted for new technicians.

Additionally, management will review the efficiency of the present method of obtaining setpoints and ranges that are corrected to water legs.

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